In rotary regenerative heat exchange apparatus a mass of heat absorbent material commonly comprised of packed element plates is first positioned in a hot gas passageway to absorb heat from hot gases passing therethrough. After the plates become heated by the hot gases they are moved into a passageway for cool air or other fluid where the then hot plates transmit their absorbed heat to the cooler air.
The heat absorbent material is carried into a rotor that rotates between hot and cool fluids, while a fixed housing including sector plates at opposite ends of the rotor is adapted to surround the rotor and direct the several fluids therethrough. To prevent mingling of the hot and cold fluids, the end edges of the rotor are provided with flexible sealing members that rub against the adjacent surface of the sector plates to accommodate a limited amount of rotor "turndown" or other distortion caused by mechanical loading or thermal deformation of the rotor.
To permit turning the rotor freely about its axis, certain minimum clearance space between the rotor seals and sector plates of the adjacent rotor housing is desirable, but excessive clearance space is to be avoided because it will dictate excessive leakage. Therefore the rotor seals are "set" to provide an optimum clearance space. Thus movement of the rotor away from the sector plates will cause excessive leakage and a lowering of effectiveness, while movement of the rotor toward the adjacent sector plates will cause interference therebetween and excessive wear.
An arrangement that provides for movement of a sector plate to accommodate thermal deformation of the rotor is shown by U.S. Pat. No. 4,124,063. The arrangement shown by this patent in most cases will provide an optimum sealing arrangement. In practice, a typical arrangement may include a sensor rod that extends axially into a housing surrounding the rotor to detect deformation. Since an extremely rapid change of temperature may produce rapid thermal deformation, interference between parts and a complete destruction of the rotor seals may occur before the usual adjusting means acts to maintain the parts at their predetermined clearance.